Why did so many twentieth century scientists and farmers focus their efforts on fertilizers and herbicides?

Agriculture of the twentieth century will be remembered for its scientific foundations and for high crop yields. The change began following a number of scientific discoveries which were to modernise agriculture and give rise to intensive production systems. Darwin [4] had put forward his theory of origin of species in 1859 with a totally new concept of the biological world. It took time for the theory to gain wide acceptance and once that happened, its implications for the evolution of improved crop varieties and new breeds of animals were not lost. Mendel’s [11] laws, which led to the concept of genes as determinants of different traits of an organism and an understanding of their mode of inheritance, provided the needed scientific methodology for this purpose. Liebig’s [10] work about the same time on the role of inorganic fertilizers in crop production provided a new insight in the field of plant nutrition, and Muller’s [12] synthesis of DDT paved the way for the use of a large number of organic pesticides for crop protection.

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